I would like to know if the forwarding rate on a device is the amount of packets it can handle in a second ?
 What is the backplane speed and how is it related to the forwading rate ?
- sn -
I would recommend reviewing the documents from the IETF Benchmarking Working Group. They provide test terminology and methodology RFCs.
Here is an example of one of the RFCs they have developed for lan switching devices:
Steve Lyons - Cisco
" I would like to know if the forwarding rate on a device is the amount of packets it can handle in a second ? "
It is. Usually measured as packets per second (pps). To be meaningful, packet size needs to be noted. Rates often quoted for 64 byte Ethernet packets.
As packet size increases pps rate drops for the same effective bandwidth.
Device pps performance can often vary depending what device is configured to do and what's the actual traffic transiting the device. For instance, ACLs may decrease pps rate.
If input rate is higher than device can forward, packets might be queued and later forwarded and/or dropped.
" What is the backplane speed and how is it related to the forwading rate ? "
Backplane speed is the bandwidth available to move traffic through the device. Measured in bits per second (bps). As noted above, pps rate can vary, based on packet size, but will use same bandwidth.
for 10 Mbps Ethernet
64 byte packets require 14,881 pps
1518 byte packets require 813 pps
If there's insufficient backplane bandwidth, packets will be queued and/or dropped.
Backplanes can be of different architectures which can greatly impact traffic transiting the device.